Polyether polyesters having anionic functionality

ABSTRACT

Polyester compositions and methods of producing and using same are provided. The polyester compositions at least include an anionic diacid monomer or diester monomer thereof and a polyether. The polyester compositions of the present invention can be effectively utilized, for example, to treat crude oil during production and refinery processing.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of Ser. No. 10/350,462 filed Jan. 24, 2003.

BACKGROUND OF THE INVENTION

The present invention relates generally to polyester compositions. Morespecifically, the present invention relates to polyether polyesters withan anionic functionality and methods of producing and using same.

In the production of oil from oil wells, the produced fluids frequentlyinclude water in the form of free water or emulsion. In general, it isnecessary to reduce the water content in order to obtain pipelinequality oil. For example, a water content of less than 1.0% in theproduced fluids is typically required.

A variety of mechanical, electrical, and chemical processes are knownand used to dehydrate oil well produced fluids and/or refined orprocessed portions thereof. With respect to chemical applications,demulsifiers can be employed. In general, a demulsifier is considered asingle or a blend of surfactant compounds in a suitable solvent systemwhich is formulated to treat a particular emulsion on an optimumcost/performance basis.

The demulsifier acts to separate oil and water, and thus the producedfluid can be more readily dehydrated to specified levels. This makes theoil well produced fluid better suited for transportation via a pipelineas previously discussed. Further, salt content can be lowered in oilrefining by a renewed formation of an emulsion with fresh water anddemulsification before distillation. In this regard, a salt content incrude oil that is too high can be problematic. For example, this cancause problematic levels of corrosion during refining.

A variety of demulsifiers are known. Typically, demulsifiers are, ingeneral, derived from alcohols, fatty acids, fatty amines, glycols andalkylphenol formaldehyde condensation products.

A need, therefore, exists to provide improved compositions that arecapable of treating crude oil to facilitate the production and refineryprocessing of same, such as breaking emulsions within the crude oil inorder to facilitate dehydration thereof.

SUMMARY OF THE INVENTION

The present invention relates generally to polyester compositions. Inparticular, the present invention relates to polyesters that arecomposed of polyethers and an anionic functionality. The compositions ofthe present invention can be effectively utilized in a number ofdifferent applications, particularly as applied to crude oil processes.

In general, the polyester compositions of the present invention at leastinclude a polyether and an anionic diacid monomer. In this regard, thecompositions of the present invention are, in general, water soluble orwater dispersible. This makes the compositions particularly suited asdemulsifiers, viscosity reducers and/or emulsion modifiers during crudeoil production and/or refinery processes.

The polyether and anionic diacid monomer can include a number ofsuitable and different materials. In an embodiment, the polyetherincludes poly(tetrahydrofuran), poly(ethylene glycol), poly(propyleneglycol), poly(butylene glycol), copolymers thereof including blockcopolymers thereof, the like and combinations thereof. The anionicdiacid monomer and diester monomers thereof can include, for example,dimethyl 5-sulfoisophthalate, sulfosuccinic acid, 4-sulfophthalic acid,sulfonaphthalic acid, the like, salts thereof including alkali salts,anhydrides thereof and combinations thereof.

In an embodiment, the present invention provides an oil-treatment agent.The oil-treatment agent includes a polyester compound composed of apolyether and an anionic diacid monomer.

In another embodiment, the present invention provides a method ofproducing a polyester composition capable of treating oil. The methodincludes processing a number of ingredients including a polyether and ananionic diacid monomer, thereby forming the polyester composition.

In yet another embodiment, the present invention provides a method oftreating oil. The method includes providing a treatment agent thatincludes a polyester composed of a polyether and an anionic diacidmonomer; and adding an effective amount of the treatment agent to oil.

An advantage of the present invention is to provide improved polyestercompositions.

Another advantage of the present invention is to provide methods ofproducing and using improved polyester compositions.

Yet another advantage of the present invention is to provide improvedpolyester polyethers having an anionic functionality that can beeffectively employed to treat oil.

Yet still another advantage of the present invention is to provideimproved polymeric compositions that can be effectively utilized todehydrate crude oil during production and refinery processing.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to polymeric compositions. Moreparticularly, the present invention relates to polyester compositionsthat have an anionic functionality. It should be appreciated that thecompositions of the present invention can be effectively utilized in anumber of different applications, particularly as applied to crude oilprocesses.

In an embodiment, the polyester compositions of the present invention atleast include a polyether and an anionic diacid monomer. In general, thecompositions are water soluble or water dispersible. This makes thecompositions particularly well-suited as demulsifiers, viscosityreducers and/or emulsion modifiers during crude oil production and/orrefinery processes.

The polyester composition of this invention is effective for resolving abroad range of hydrocarbon emulsions encountered in crude oilproduction, refining and chemical processing. Typical hydrocarbonsinclude crude oil, refined oil, bitumen, condensate, slop oil,distillates, fuels and mixtures thereof. The polyester composition isalso useful for resolving emulsions in butadiene, styrene, acrylic acid,and other hydrocarbon monomer process streams.

The polyester composition of this invention is particularly effective ona varying slate of crude oil types. For example, the polyestercomposition is effective at rapid, substantial demulsification of oiland production of dry residual oil. Further, it is believed that thepolyester composition of the present invention can afford an increasedbiodegradation relative to existing demulsifiers and the like. Thewater-soluble nature of the present invention allows the use of water asa solvent and carrier fluid. This can provide a significant cost savingsand environmental benefits by reducing organic solvent use.

The polyether and anionic diacid monomer can include a number ofsuitable and different materials. In an embodiment, the polyetherincludes poly(tetrahydrofuran), poly(ethylene glycol), poly(propyleneglycol), poly(butylene glycol), copolymers thereof including blockcopolymers thereof, such as, poly(ethylene glycol)-block-poly(propyleneglycol)-block-poly(ethylene glycol), poly(propyleneglycol)-block-poly(ethylene glycol)-block-poly(propylene glycol),poly(ethylene glycol)-block-poly(tetrahydrofuran)-block-poly(ethyleneglycol), poly(propyleneglycol)-block-poly(tetrahydrofuran)-block-poly(propylene glycol), andpoly(ethylene-ran-propylene glycol), the like and combinations thereof.

The anionic diacid monomer comprises an aryl group such as phenyl,naphthyl, and the like substituted with two carboxylate groups and atleast one additional anionic functional group. Typical carboxylategroups include carboxylic acids, carboxylic esters, carboxylicanhydrides, and the like, and mixtures thereof.

The anionic functional group can include any functional group thatpossesses a negative charge at a certain pH. Representative anionicfunctional groups include carboxylate, sulfonate, sulfate, phosphonate,phosphate, phosphite and the like, or an organic aliphatic or aromaticmoiety substituted by at least one of the foregoing.

In an embodiment, the anionic diacid monomer and can include, forexample, dimethyl 5-sulfoisophthalate, sulfosuccinic acid,4-sulfophthalic acid, sulfonaphthalic acid, the like, salts thereof,anhydrides thereof and combinations thereof.

In an embodiment, the polyester composition of the present invention hasthe following formula:(A)_(x) (B)_(y)

-   -   where A is the anionic diacid monomer, B is the polyether, and x        and y are independently integers of 1 to about 250. Preferably,        the anionic diacid monomer or diester monomer thereof has the        following formula:

In an embodiment, the (B)_(y) component can include one or anycombination of polyethers as represented by the following formulas:

-   -   where z ranges from 1 to about 100, preferably from 2 to about        40;    -   where n ranges from 1 to about 150, preferably from about 6 to        about 35;    -   where n ranges from 1 to about 150, preferably from about 5 to        about 40;    -   where m ranges from 1 to about 150, preferably from 2 to about        50, and where n ranges from 1 to about 150, preferably from 2 to        about 50;    -   where m ranges from 1 to about 150, preferably from 2 to about        50, and where n ranges from 1 to about 150, preferably from 2 to        about 50;    -   where R is an alkyl, —H, —CH₃ or the like, and where n ranges        from 1 to about 150, preferably about 5 to about 40;    -   where m ranges from 1 to about 150, preferably from 2 to about        50, and where n ranges from 1 to about 150, preferably from 2 to        about 33; and    -   where m ranges from 1 to about 150, preferably from 2 to about        50, and where n ranges from 1 to about 150, preferably from 2 to        about 33.

In a preferred embodiment, the polyester composition has the followingformula:

-   -   where R is an anionic functional group; m ranges from 1 to about        150, preferably 2 to about 50; n ranges from 1 to about 150,        preferably 2 to about 50; x any y independently range from 0 to        about 250, provided that x and y are not both 0; and z ranges        from 1 to about 100, preferably 2 to about 40.

In another preferred embodiment, R is selected from carboxylate,sulfonate, sulfate, phosphonate, phosphate, phosphite and an organicaliphatic or aromatic moiety substituted by at least one fromcarboxylate, sulfonate, sulfate, phosphonate, phosphate, or phosphitegroup.

In another preferred embodiment, R is sulfonate.

The polyester compositions can be characterized in a number of suitableand different ways. In an embodiment, the number average molecularweight ranges from about 500 to about 20,000, preferably from about 500to about 8,000, such as from about 574 to about 6300.

The polyester compositions of the present invention can be made in avariety of suitable ways. In general, the polymeric compositions aremade by processing a number of different ingredients or reactants atleast including a polyether and an anionic diacid monomer or diestermonomer thereof. The reactants can be processed in any suitable reactionand under any suitable process conditions with respect to, for example,temperature, pressure and/or the like.

As previously discussed, the polyester compositions of the presentinvention can be effectively utilized in a number of differentapplications, particularly as applied during crude oil production andrefinery processing. In general, the polyester composition can be addedto the crude oil or other treatable fluid in any suitable effectiveamount and in any suitable manner.

In an embodiment, the polyester composition is provided in a suitablecarrier such as water, aliphatic solvents such as kerosene and aromaticsolvents such as heavy aromatic naphtha at any suitable concentration. Apreferred carrier solvent is water. In an embodiment, the concentrationof the polyester composition in the carrier solvent ranges from about 1%by weight to about 60% by weight, preferably from about 30% by weight toabout 50% by weight.

The polyester composition can be added to the crude oil or the like inany suitable manner as previously discussed. Preferably, the polyestercomposition is dissolved in a carrier solvent as discussed above andsubsequently added to the crude. In an embodiment, the polyestercomposition in liquid form can be diluted with an appropriate solvent,preferably water, in any suitable volume ratio prior to adding thepolyester composition to the crude. In an embodiment, the volume ratioof dilution solvent (i.e., water) to polyester composition in liquidform is at least about 5 to about 1.

It should be appreciated that the polyester composition of the presentinvention can be adapted in any suitable way for treatment purposes. Forexample, the polyester composition may be dissolved in a carrier solventand then added directly to the crude or the like without furtherdilution. Also, the polyester composition may be added to the crude orthe like in dry form.

The polyester composition may be used alone or in combination with anyof a number of additional demulsifiers known in the art includingalcohols, fatty acids, fatty amines, glycols and alkylphenolformaldehyde condensation products. The polyester composition may alsobe used in combination with corrosion inhibitors, viscosity reducers andother chemical treatments used in crude oil production, refining andchemical processing.

By way of example and not limitation, the following examples illustratehow the polyester compositions according to an embodiment of the presentinvention can be made:

EXAMPLE ONE

4.30 grams (“g”) of poly(tetrahydrofuran) was charged into a suitablereactor and maintained at greater than 70° C. The number averagemolecular weight of the poly(tetrahydrofuran) was about 1400. Next, 4.54g of poly(ethylene glycol)-block-poly(propyleneglycol)-block-poly(ethylene glycol) was charged into the reactor. Theblock copolymer had a molecular weight of about 2900 at about 40% byweight of ethylene oxide (“EO”). Next, 1.16 g of dimethyl5-sulfoisophthalate was charged into the reactor. Then, 0.008 g ofsodium acetate was charged into the reactor. 0.015 g of titaniumbutoxide was then charged into the reactor while stirring vigorously.The reactor was purged with nitrogen gas under heat at about 200° C. Thetemperature was maintained at about 200° C. for about 5 hours. Theresultant polyester product was cooled and transferred from the reactor.

EXAMPLE TWO

4.28 g of poly(tetrahydrofuran) at a molecular weight of approximately1,000 was charged into a reactor at a temperature greater than 70° C.4.12 g of poly(ethylene glycol)-block-poly(propyleneglycol)-block-poly(ethylene glycol) at a molecular weight approximatelyequal to 1900 and 50% EO was charged into the reactor. Next, 1.60 gdimethyl 5-sulfoisophthalate was charged into the reactor which wassubsequently followed by a charge of 0.008 g sodium acetate. The reactorwas then charged with 0.015 g titanium butoxide while stirringvigorously. Next, the reactor was purged with nitrogen gas and heated toabout 200° C. The reactor was maintained at this temperature for about 5hours. The resultant polyester product was cooled and transferred fromthe reactor.

EXAMPLE THREE

5.10 g of poly(tetrahydrofuran) at a molecular weight approximatelyequal to 1400 was charged into the reactor wherein the temperature wasmaintained at greater than 70° C. Next, 5.35 g of poly(ethyleneglycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) at amolecular weight of approximately 1900 at 50% EO was charged into thereactor. The reactor was then charged with 1.38 g dimethyl5-sulfoisophthalate and subsequently charged with 0.008 g sodiumacetate. Next, 0.015 g of titanium butoxide was charge into the reactorwhile stirring vigorously. The reactor was purged with nitrogen gas andheated to about 200° C. The temperature was maintained at about 200° C.for about 5 hours. The resultant product was cooled and transferred fromthe reactor.

EXAMPLE FOUR

148.32 g of poly(tetrahydrofuran) at a molecular weight of approximately2000 was charged into the reactor and maintained at a temperaturegreater than 70° C. 68.04 g poly(ethylene glycol)-block-poly(propyleneglycol)-block-poly(ethylene glycol) at an approximate molecular weightof 1900 and at 50% EO was then charged into the reactor. The reactor wasnext charged with 26.52 g dimethyl 5-sulfoisophthalate. Then, 0.18 gsodium acetate was charged into the reactor. A charge of 0.36 g titaniumbutoxide was added into the reactor while stirring vigorously. Thereactor was purged with nitrogen gas and heated to about 200° C. Thistemperature was maintained at about 200° C. for about 5 hours. Theresultant product was cooled and transferred.

EXAMPLE FIVE

A charge of 6.88 g poly(tetrahydrofuran) at a molecular weightapproximately equal to 2900 was added to a reactor and maintained at atemperature greater than 70° C. Then, 2.24 g poly(ethyleneglycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) at amolecular weight approximately equal to 1900 and at 50% EO was chargedinto the reactor. A charge of 0.87 g dimethyl 5-sulfoisophthalate wasnext added to the reactor. 0.008 g of sodium acetate was charged intothe reactor, subsequently followed by a charge of 0.015 g titaniumbutoxide while stirring vigorously. The reactor was purged with nitrogengas and heated to about 200° C. This temperature was maintained at about200° C. for about 5 hours. The resultant product was cooled andtransferred from the reactor.

EXAMPLE SIX

5.17 g of poly(tetrahydrofuran) at a molecular weight approximatelyequal to 1000 was charged into the reactor and maintained at atemperature greater than 70° C. A charge of 2.88 g poly(ethyleneglycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) at amolecular weight approximately equal to 1100 and at 10% EO was added tothe reactor. Next, 1.94 g dimethyl 5-sulfoisophthalate was charged intothe reactor, subsequently followed by a charge of 0.008 g sodiumacetate. Then, 0.015 g titanium butoxide was charged into the reactorwhile stirring vigorously. The reactor was purged with nitrogen gas andheated to about 200° C. The temperature was maintained at about 200° C.for about 5 hours. The resultant product was cooled and transferred fromthe reactor.

Tests were conducted on the polyester compositions made in accordancewith an embodiment of the present invention. In particular, a BottleTest, a PED Test and a Viscosity Reduction Test were conducted todemonstrate the beneficial effects of the present invention as describedbelow in greater detail.

Bottle Test

Samples of a crude oil emulsion (100 mL; API gravity=18) were placed ingraduated prescription bottles and heated to 180° F. in a water bath.The heated samples were treated with 500 ppm by weight of the polyestercomposition made pursuant to each of Example 1-6 as discussed above. Thetreated crude samples were then shaken for 10 minutes to mix theadditive (i.e., polyester composition) into the crude oil. The sampleswere then returned to the water bath at 180° F. After 15 minutes, thesamples were removed from the water bath. Any free water that hasseparated from the crude emulsion was then recorded. The sample was thenreturned to the hot water bath. Free water readings were repeatedlytaken at 30, 45, 60, 90 and 120 minutes.

After 120 minutes, a 5 mL sample of the crude oil was taken from a pointapproximately 15 mL above the level of the free water. The crude samplewas diluted with 5 mL hydrocarbon solvent in a graduated centrifuge tubeand shaken vigorously. The diluted sample was placed in a centrifuge athigh speed for 10 minutes. The centrifuged sample was removed and freewater (W) and residual emulsion (BS) levels were then recorded. Next,the samples were then treated with a slugging compound to coalesce allof the remaining water in the sample. The treated samples were shakenvigorously and centrifuged. The centrifuged sample was removed and thetotal free water (Slug) was recorded. The results of the Bottle Test areindicated below in Table I. TABLE I Water Drop (minutes) Thief GrindoutProduct 15 30 45 60 90 120 B.S. W Slug Comparative 15 22 23 24 25 26 1.20.8 2.4 Sample Sample 1 13 24 25 26 26 27 4.2 0.6 5.0 Sample 2 3 18 2325 27 27 Trace 3.6 4.0 Sample 3 3 22 24 26 27 27 2.4 0.0 2.4 Sample 4 623 24 25 26 27 3.0 0.4 3.4 Sample 5 6 24 26 27 27 28 2.8 0.4 3.2 Sample6 3 10 20 23 25 27 3.6 0.8 4.2 Blank — — 1 1 1 1

As shown in Table I, the polyester composition made pursuant to anembodiment of the present invention displayed effective demulsifierproperties based on the Bottle Test. In this regard, crude oil Samples1-6 were treated with a polyester composition made pursuant to Examples1-6, respectively. The Bottle Test was also conducted on a blank sampleand a comparative crude oil sample that was treated with a commerciallyavailable demulsifier.

PED Test

The PED (“Portable Electric Desalter”) test is a static test to comparethe relative efficiencies of emulsion breaker formulations. Awater-in-oil emulsion was prepared under controlled conditions in ablender. The emulsion was poured into glass tubes. The tubes were placedinto the PED unit where the emulsion was resolved with the assistance ofheat and electric field. The resolution of the emulsion was noted by thevolume of water resolved during the period of time of testing. Thevolume of water and the speed at which it separated were used forcomparison of the efficiency of the test formulations which includedProducts A-D each treated with 6 ppm of a commercially availablechemical and Sample 4 treated with 6 ppm of polyester composition madepursuant to Example 4 discussed above. Two power levels were used duringthe testing, based on the API gravity of the crude (38.5° API at 72°F.). The blending time was ten seconds during the studies conducted.After about 7 to 8 minutes of heating, a voltage of 3000 volts wasapplied for one minute. In the testing, an additional voltage of 500volts was applied in about 17 to about 18 minute time interval. The timeperiod for the testing was 30 minutes. The temperature of the testingwas maintained at about 205° F. The maximum water separation is 3.75milliliters for a 5% wash water concentration at pH 5.5. The testresults are indicated below in Table II. TABLE II WATER SEPARATION INMILLILITERS AT TIME INDICATED: PRODUCT 5 MIN. 10 MIN. 15 MIN. 20 MIN. 30MIN. BLANK 1.00 2.40 2.40 2.50 2.70 Product A 2.10 2.80 2.80 2.80 2.90Product B 2.50 3.00 3.00 3.00 3.10 Product C 3.00 3.60 3.70 3.75 3.75Product D 2.20 3.30 3.30 3.50 3.10 Sample 4 2.10 3.00 3.00 3.00 3.00Viscosity Reduction Test

Samples of a crude oil emulsion were heated in a water bath at 180° F.Each crude sample (Samples 1-5 and Comparative Sample) were treated with300 ppm by weight of an additive. Samples 1-5 were treated with thepolyester compositions made pursuant to Examples 1-5, respectively, asdiscussed above. The comparative sample was treated with acommercially-available chemical. A blank run was also conducted. Theviscosity reducing additive was thoroughly mixed with the crude. Thetreated crude was placed in a thermostatic viscometer at 180° F.Viscosity data was collected over time as shown below in Table III.TABLE III Viscosity (Centipoise) Time Incumbent (Minutes) Blank ChemicalSample 1 Sample 2 Sample 3 Sample 4 Sample 5 5 5039 3575 3239 3911 36233167 3719 30 4775 2136 1680 2471 2328 1896 2280 60 4223 1584 1464 19921752 1488 1680 90 4175 1104 1080 1368 1272 1008 1320 120 4079 984 9841008 1008 864 1056 150 4175 936 816 888 840 768 960 180 4199 960 744 888816 720 936 210 4271 960 744 888 744 672 816

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

1. A method of treating oil, the method comprising the steps of: providing a treatment agent that includes a polyester composed of a polyether and an anionic diacid monomer or diester thereof; and adding an effective amount of the treatment agent to oil.
 2. The method of claim 1 wherein the anionic diacid monomer or diester thereof is selected from the group consisting of dimethyl 5-sulfoisophthalate, sulfosuccinic acid, 4-sulfophthalic acid, sulfonaphthalic acid, salts thereof, anhydrides thereof and combinations thereof.
 3. The method of claim 1 wherein the polyether is selected from the group consisting of poly(tetrahydrofuran), poly(ethylene glycol), poly(propylene glycol), poly(butylene glycol), copolymers thereof, and combinations thereof.
 4. The method of claim 1 wherein the polyester has the formula (A_(x) (B)_(y) where A is the anionic diacid monomer or diester thereof, where B is the polyether, and where x and y are independently integers of 1 to about
 250. 5. The method of claim 4 wherein A includes dimethyl 5-sulfoisophthalate, sodium salt.
 6. The method of claim 4 wherein (B)_(y) has a formula selected from the group consisting of

where z ranges from 1 to about 100;

where n ranges from 1 to about 150;

where n ranges from 1 to about 150;

where m ranges from 1 to about 150; and where n ranges from 1 to about 150;

where m ranges from 1 to about 150, and where n ranges from 1 to about 150;

where R is selected from the group consisting of an alkyl group, —H, and —CH₃, and where n ranges from 1 to about 150;

where m ranges from 1 to about 150, and where n ranges from 1 to about 150;

where m ranges from 1 to about 150, and where n ranges from 1 to about 150; copolymers thereof and combinations thereof.
 7. The method of claim 1 wherein the polyester has the formula

where R is an anionic functional group; m ranges from 1 to about 150; n ranges from 1 to about 150; x and y independently range from 0 to about 250, provided that x and y are not both 0; and z ranges from 1 to about
 100. 8. The method of claim 7 wherein where m ranges from 2 to about 50; n ranges from 2 to about 50; and z ranges from 2 to about
 40. 9. The method of claim 7 wherein the polyester compound has a number average molecular weight that ranges from about 500 to about 20,000.
 10. The method of claim 11 wherein the anionic diacid monomer is selected from the group consisting of dimethyl 5-sulfoisophthalate, sulfosuccinic acid, 4-sulfophthalic acid, sulfonaphthalic acid, salts thereof, anhydrides thereof and combinations thereof; and wherein the polyether is selected from the group consisting of poly(tetrahydrofuran), poly(ethylene glycol), poly(propylene glycol), poly(butylene glycol), copolymers thereof, and combinations thereof.
 11. The method of claim 1 wherein the treatment agent is capable of demulsifying crude oil during production or processing thereof.
 12. The method of claim 1 wherein the treatment agent is capable of reducing oil viscosity during crude oil production or processing.
 13. The method of claim 1 wherein the treatment agent is capable of modifying emulsions in crude oil production or processing.
 14. The method of claim 1 wherein the treatment agent is added to the oil in liquid form.
 15. The method of claim 14 wherein the liquid form is prepared by dissolving the polyester in an aqueous carrier medium.
 16. The method of claim 15 wherein a concentration of the polyester in the liquid form ranges from about 1% by weight to about 60% by weight.
 17. The method of claim 16 wherein the polyester in liquid form is diluted prior to addition to the oil.
 18. The method of claim 1 wherein the oil-treatment agent further comprises a demulsifier in liquid form used during crude oil production or processing.
 19. The method of claim 1 wherein the oil-treatment agent further comprises a viscosity reducer used during crude oil production or processing.
 20. The method of claim 1 wherein the oil-treatment agent further comprises an emulsion modifier used during crude oil production or processing. 